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Mars Pathfinder Update - October 29, 1997

PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011 
http://www.jpl.nasa.gov

                  MARS PATHFINDER MISSION STATUS
                         October 29, 1997

     Mars Pathfinder's operations team is continuing daily efforts 
to reestablish communications with the lander. Over the last month 
the team has been working through all credible problem scenarios 
and taking a variety of actions to try to recover the link with 
Pathfinder. They plan to continue sending commands to the 
spacecraft for another week before shifting to a contingency plan 
of less frequent commanding and listening. 

     During the past month, the team has investigated a variety of 
scenarios that could explain why the Pathfinder lander has not 
sent telemetry to Earth since September 27. Since that time, 
ground stations have detected a carrier signal from the lander on 
two occasions, but on each attempt following the receipt of the 
carrier signals they were not able to reestablish a link, and 
therefore no digital data was received to enable determination of 
the spacecraft's condition.

     The team initially investigated the possibility that the 
lander's battery had failed. This scenario would have resulted in 
spacecraft clock uncertainties and unknown spacecraft power 
conditions due to the lander only operating on solar power. They 
then investigated the possibility that, because the lander's 
transmitter had been turned off for many days, the lander's 
temperature had dropped to a range between -50  and -30 C (-58 to 
-22 F), some 20 to 40 degrees C (about 35 to 70 degrees F) colder 
than previous operating temperatures, causing its radio receiver 
to shift away from its normal frequency range.

     Currently the team is sending commands to the lander to 
investigate the possibility that the spacecraft's flight computer 
is not operating normally. "Under this scenario, the thought is 
that perhaps the computer is not booting up fully," said Mission 
Manager Richard Cook. "The team is sending resets to the lander at 
various times of the day before we attempt to send other 
commands."

     All scenarios are expected to have been fully investigated by 
end of day on Tuesday, November 4. If the team does not 
reestablish contact by then, said Project Manager Brian Muirhead, 
they plan on shifting to a contingency strategy of sending 
commands to the lander only periodically, perhaps once a week or 
once per month. "The normal extended mission would be over, but 
there is still a small chance of reestablishing a link, so we'll 
keep trying at a very low level," Muirhead said. "Of course the 
science team will continue to process, catalog and understand the 
large volume of science data we have received, which will keep us 
very busy for several months."

     Although the true cause of the loss of lander communications 
may never be known, recent events are consistent with predictions 
made at the beginning of the extended mission in early August. 
When asked about the life expectancy of the lander, project team 
members predicted that the first thing that would fail on the 
lander would be the battery; this apparently happened after the 
last successful transmission September 27. After that, the lander 
would begin getting colder at night and go through much deeper 
day-night thermal cycles. Eventually, the cold or the cycling 
would probably render the lander inoperable. According to 
Muirhead, it appears that this sequence of events may have taken 
place. The health and status of the rover is also unknown, but 
since initiating its onboard backup operations plan three weeks 
ago, it is probably in the vicinity of the lander attempting to 
communication with the lander.

     At the time the last telemetry from the spacecraft was 
received, Pathfinder's lander had operated nearly three times its 
design lifetime of 30 days, and the Sojourner rover operated 12 
times its design lifetime of seven days. Since its landing on July 
4, 1997, Mars Pathfinder has returned 2.6 billion bits of 
information, including more than 16,000 images from the lander and 
550 from the rover, as well as more than 15 chemical analyses of 
rocks and extensive data on winds and other weather factors. The 
only remaining objective was to complete the high-resolution 360-
degree image of the landing site called the "Super Pan," of which 
83 percent has already been received and is being processed.

     Daily audio updates on Mars Pathfinder's status are available 
by calling (800) 391-6654. 

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